Drilling rigs employ hydraulically actuated wrenches to tighten and loosen the threaded connections between drill pipes. These wrenches comprise two pairs of opposed jaws, one for the male-threaded pipe and the other for the female-threaded pipe of the adjacent components of the drill string. Each wrench is adapted to clamp around a pipe section, one above and the other below the threaded connection. At least one clamping component of the wrench assembly will pivot with respect to another clamping component so as to twist one of the pipe sections with respect to the other. There are two common problems that are not adequately addressed by conventional wrench assemblies. The first is misalignment of the drill pipe string with the wrench assembly due to one or more pipe sections being bent or misaligned. This condition interferes with the ability of the wrench assembly to clamp effectively onto the pipe sections and therefore jeopardizes the ability of the wrench to tighten or loosen the joint between adjacent pipe sections. The other problem arises from inadvertent axial movement (with respect to the drill string) of the drill rig carriage (on which the wrench assembly is mounted) while the clamping components of the wrench assembly are clamped onto the drill pipes. Such axial movement while the pipe sections are clamped can damage the drill pipes, the wrench assembly and other components of the drill rig.
It is known to provide wrench assemblies that are adapted for use with drill pipes of various diameters. Such assemblies are described in U.S. Patent Application Publication No. 2009/0255662 and U.S. Pat. No. 7,665,514. It is also known to provide wrench assemblies that are adapted for use with drill pipes having wall thicknesses that have become tapered through wear. Such assemblies are described in U.S. Pat. No. 6,938,519 and U.S. Pat. No. 6,814,149. It is also known to provide pipe guide assemblies that are adapted to guide or position a drill pipe for engagement by a pipe gripping apparatus. Such assemblies are described in U.S. Patent Application Publication No. 2009/0056930 and U.S. Pat. No. 7,090,254. Finally, U.S. Patent Publication No. 2010/0200258 describes a wrench assembly that is adapted to automatically disengage from the pipe sections if the pipe is raised or lifted, such as for example, if the operator inadvertently withdraws the pipe from the drill hole without first disengaging the wrench assembly.
It would be desirable, however, if a wrench assembly could be provided on a drill rig so as to have some freedom of movement in three axes. A preferred embodiment of such a wrench assembly would be self-orienting when clamped onto misaligned pipe sections, and it would also deflect without damage when an axial force is inadvertently applied while the wrenches of the assembly are clamped onto adjacent pipe sections of a drill string.
Notes on Construction
The use of the terms “a”, “an”, “the” and similar terms in the context of describing the invention are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising”, “having”, “including” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The terms “substantially”, “generally” and other words of degree are relative modifiers intended to indicate permissible variation from the characteristic so modified. The use of such terms in describing a physical or functional characteristic of the invention is not intended to limit such characteristic to the absolute value which the term modifies, but rather to provide an approximation of the value of such physical or functional characteristic.
The use of any and all examples or exemplary language (e.g., “such as”) herein is intended merely to better illuminate the invention and not to place a limitation on the scope of the invention. Nothing in the specification should be construed as indicating any element as essential to the practice of the invention unless so stated with specificity.
Various terms are specifically defined herein. These terms are to be given their broadest possible construction consistent with such definitions, as follows:
The terms “lower” and “below” and similar terms of relative position refer to the part of the wrench assembly nearest the ground on which the drill rig is placed when drilling.
The terms “upper” and “above” and similar terms or relative position refer to the part of the wrench assembly opposite the lower part.
The term “linear actuator” refers to an electric, hydraulic or electro-hydraulic device that generates force which is directed in a straight line. One common example of a linear actuator is a fluid actuator which includes a cylinder, a piston within the cylinder, and a rod attached to the piston. By increasing the pressure within the cylinder on one side of the piston (over that on the opposite side of the piston), the rod will extend from the cylinder or retract into the cylinder.
The terms “pipe section”, “drill pipe section” and similar terms refer to a hollow tubular component that is provided with male threads on one end and corresponding female threads on the other, and is intended to be connected by threaded engagement, or is connected by threaded engagement, to an adjacent pipe section.
The terms “drill pipe”, “drill string” and similar terms refer to a plurality of pipe sections that are joined together by threaded engagement, with a drill bit or other boring component at the lower end thereof.
The term “adjacent pipe sections” and similar terms refer to a pair of pipe sections that are joined together by threaded engagement to form a part of a drill string, or are located or placed with respect to each other so as to be joined together in such manner, or have been disengaged from each other.